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Patents: 133 of 530	UNITED STATES PATENT OFFICE JOSHUA K. INGALLS, OF NEW YORK, N. Y. ILLUMINATING-TILE.	Joshua K. Ingalls 5 of 7
SPECIFICATION forming part of Letters Patent No. 258,232, dated May 23, 1882. Application filed January 12, 1882. (No model.)

To all whom it may concern:      Be it known that I, JOSHUA K. INGALLS, a citizen of the United States, residing at the city, county, and State of New York, have invented certain improvements in Illuminating-Tiles, of which the following is a specification.     This invention relates in part to the construction and setting of the illuminating-lenses and in part to the metallic frame or plate in which said lenses are set, the objects being in part to prevent the pendent lenses from being broken by unequal expansion, in part to prevent the exposed surface of the lens from being dimmed by collections of dirt thereon, in part to enable the lenses to be set evenly and firmly in their sockets, and in part to provide for the better transmission of the light by reflection and refraction into the rooms below the sidewalk or the roof in which the lenses are placed.     The novel features of the invention will be fully set forth, and defined in the claims.     In the drawings, which serve to illustrate my invention, Figure 1 is a fragmentary plan of an illuminating-tile embodying my improvements. Fig. 2 is a vertical section of the same on the line 2 2 in Fig. 1, looking in the direction indicated by arrow 2. Fig. 3 is a vertical section on the line 3 3 in Figs. 1 and 2, looking in the direction indicated by arrow 3; and Fig. 4 is an under side plan view of one of the lenses detached.     Let A represent the socket-plate, generally made from cast metal, and B the lenses, set in sockets therein, in alternate order by preference. The plate has elevations or studs a a and b b formed on its upper face, which perform several important functions that will be referred to more particularly hereinafter, and has sockets or apertures c c formed in it to receive the lenses. These sockets are slightly spheroidal in form, and the opening at the upper side of the plate is a little larger than that at the lower side, whereby the lenses are properly supported and prevented from falling through. The lens-- preferably circular in plan, but not necessarily so-- has several peculiarities of construction. On its upper face, occupying about one-half its width by preference, is formed an inclined plane, d, the end d' of which is elevated about as high above the general level of the top of

the lens as the studs a and b rise above the general level of the plate A. This plane runs down to the general level of the top of the lens at its other end, d². The portion e of the lens, which rests in the socket c, is made slightly spheroidal, to conform nearly to the shape of the socket, being a little smaller than the same, to make room for the cement f employed in setting the lenses. On this part of the lens are formed several thin projecting ribs, g g. (Seen best in Fig. 4.) The roughness and irregularity of the sockets, due to unequal shrinkage in casting and to other causes, sometimes prevent the unyielding lenses from being properly set to the same uniform depth.     By providing the lenses with ribs g g so thin and fragile as to be crushed off by pressing the lenses into their sockets, I am enabled to bring all of the lenses down to the proper level before the cement is run in, as will be readily understood. The pendent portion h of the lens is in the form of a cylindrical ungula, the oblique side h' being an elliptic or parabolic curve by preference, as shown in Fig. 3. Where the horizontal section or the plan of the lens is not a circle this pendent portion would approach more nearly to the form of a prismatic ungula, as will be well understood. The vertical rays of light, which are the strongest, enter the lens through the inclined plane d, and, being refracted by the inclined surface, strike the curved or inclined anterior face, h', at at angle more obtuse than would be the case if the plane d were not inclined. From this face the rays are reflected back into the room, as indicated by the arrow 4 in Fig. 2.     It will be observed that the part e of the lens is joined to the pendent part h by a sweep or curve, and that all sharp or re-entering angles or shoulders are avoided. The object of this is to prevent the pendent portion from breaking off under the strain caused by un-equal expansion and contraction. In winter, for example, the upper exposed part, e, will be cold, while the pendent part will be warm, owing to its protected interior position, and if a neck or shoulder were formed at the junction the lens would inevitably break at this point. By making the inferior portion of the lens merely a continuation of the superior portion, and avoiding abrupt offsets at their junction, I avoid all danger of breaking from this cause.